Methods of forming structures and methods of decreasing defect density

ABSTRACT

A method of forming a structure comprises forming a pattern of self-assembled nucleic acids over a material. The pattern of self-assembled nucleic acids is exposed to at least one repair enzyme to repair defects in the pattern. The repaired pattern of self-assembled nucleic acids is transferred to the material to form features therein. A method of decreasing defect density in self-assembled nucleic acids is also disclosed. Self-assembled nucleic acids exhibiting an initial defect density are formed over at least a portion of a material and the self-assembled nucleic acids are exposed to at least one repair enzyme to repair defects in the self-assembled nucleic acids. Additional methods are also disclosed.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.15/606,601, filed May 26, 2017, pending, which is a continuation of U.S.patent application Ser. No. 14/997,108, filed Jan. 15, 2016, abandoned,which is a divisional of U.S. patent application Ser. No. 14/151,635,filed Jan. 9, 2014, now U.S. Pat. No. 9,275,871, issued Mar. 1, 2016,the disclosure of each of which is hereby incorporated herein in itsentirety by this reference.

FIELD

The present disclosure, in various embodiments, relates generally tonanostructures comprising self-assembled nucleic acids and exhibitinglow defect density, and to methods of preparing such nanostructures.

BACKGROUND

A continuing goal of integrated circuit fabrication is to decrease thedimensions thereof. Integrated circuit dimensions can be decreased byreducing the dimensions and spacing of the constituent features orstructures. For example, by decreasing the dimensions and spacing ofsemiconductor features (e.g., storage capacitors, access transistors,access lines) of a memory device, the overall dimensions of the memorydevice may be decreased while maintaining or increasing the storagecapacity of the memory device.

As the dimensions and spacing of semiconductor device features becomesmaller, conventional lithographic processes become increasingly moredifficult and expensive to conduct. Therefore, significant challengesare encountered in the fabrication of nanostructures, particularlystructures having a feature dimension (e.g., critical dimension) lessthan a resolution limit of conventional photolithography techniques(currently about 50 nm). It is possible to fabricate semiconductorstructures of such feature dimensions using a conventional lithographicprocess, such as shadow mask lithography and e-beam lithography.However, use of such processes is limited because the exposure tools areextremely expensive or extremely slow and, further, may not be amenableto formation of structures having dimensions of less than 50 nm.

The development of new processes, as well as materials useful in suchprocesses, is of increasing importance to make the fabrication ofsmall-scale devices easier, less expensive, and more versatile. Oneexample of a method of fabricating small-scale devices that addressessome of the drawbacks of conventional lithographic techniques isself-assembled block copolymer lithography.

Although self-assembled block copolymer lithography is useful forfabrication of semiconductor structures having dimensions of less than50 nm, there are still problems that must be addressed. Self-assembledblock copolymer materials may not provide nanostructures exhibitingsufficiently low defect levels.

Self-assembled nucleic acids have been researched for formingsemiconductor devices. The specificity of complementary base pairing innucleic acids provides self-assembled nucleic acids that may be used forself-assembled nucleic acid lithography processes.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a flowchart diagram showing a method of forming nanostructuresin accordance with one embodiment of the present disclosure;

FIG. 2A shows self-assembled “multi-stranded” nucleic acids according toone embodiment of the present disclosure;

FIG. 2B shows self-assembled “scaffolded” nucleic acids according to oneembodiment of the present disclosure;

FIG. 2C shows self-assembled “single-stranded” nucleic acids accordingto one embodiment of the present disclosure; and

FIGS. 3A-3C are cross-sectional views of various stages of usingself-assembled nucleic acids as nano-scale templates or masks totransfer the desired pattern to the substrate, according to oneembodiment of the present disclosure.

DETAILED DESCRIPTION

The following description provides specific details, such as materialtypes, material thicknesses, and processing conditions in order toprovide a thorough description of embodiments of the disclosure.However, a person of ordinary skill in the art will understand thatembodiments of the present disclosure may be practiced without employingthese specific details. Indeed, the embodiments of the presentdisclosure may be practiced in conjunction with conventional fabricationtechniques employed in the industry.

In addition, the description provided herein does not form a completeprocess flow for forming nanostructures. Only those process acts andstructures necessary to understand the embodiments of the presentdisclosure are described in detail below. Additional acts to form thecomplete nanostructures may be performed by conventional fabricationtechniques. Also the drawings accompanying the application are forillustrative purposes only, and are thus not necessarily drawn to scale.Elements common between figures may retain the same numericaldesignation. Furthermore, while the materials described and illustratedherein may be formed as layers, the materials are not limited theretoand may be formed in other three-dimensional configurations.

As used herein, the singular forms “a,” “an,” and “the” are intended toinclude the plural forms as well, unless the context clearly indicatesotherwise.

As used herein, the term “nucleic acid” means and includes a polymericform of nucleotides (e.g., polynucleotides and oligonucleotides) of anylength that comprises purine and pyrimidine bases, or chemically orbiochemically modified purine and pyrimidine bases. Nucleic acids maycomprise single stranded sequences, double stranded sequences, orportions of both double stranded or single stranded sequences. Asnon-limiting example, the nucleic acid may include ribonucleic acid(RNA), deoxyribonucleic acid (DNA), peptide nucleic acid (PNA), orcombinations thereof. The backbone of the polynucleotide may comprisesugars and phosphate groups as may typically be found in RNA or DNA, ormodified sugar and/or phosphate groups. Furthermore, the polynucleotidemay comprise modified nucleotides, such as methylated nucleotides andnucleotide analogs.

As used herein, the term “substrate” means and includes a base materialor a construction upon which additional materials are formed.Non-limiting example of the substrates may include glass, mica,polystyrene, polypropylene, polyamides, polyesters, polyacrylates,polyvinylchloride, polycarbonate, fluoropolymers, fluorinated ethylenepropylene, polyvinylidene, polydimethylsiloxane, silicon, metals (e.g.,gold, silver, titanium), and stainless steel.

In some embodiments, the substrate may be a semiconductor substrate, abase semiconductor material on a supporting structure, a metalelectrode, or a semiconductor substrate having one or more materials,structures or regions formed thereon. By way of non-limiting example,the semiconductor substrate may be a conventional silicon substrate, orother bulk substrate comprising a layer of semiconductive material. Asused herein, the term “bulk substrate” means and includes not onlysilicon wafers, but also silicon-on-insulator (SOI) substrates,silicon-on-sapphire (SOS) substrates and silicon-on-glass (SOG)substrates, epitaxial layers of silicon on a base semiconductorfoundation, or other semiconductor or optoelectronic materials, such assilicon-germanium (Si_(1-x)Ge_(x), where x is, for example, a molefraction between 0.2 and 0.8), germanium (Ge), gallium arsenide (GaAs),gallium nitride (GaN), or indium phosphide (InP), among others.Furthermore, when reference is made to a “substrate” in the followingdescription, previous process acts may have been conducted to formmaterials, regions, or junctions in or on the base semiconductorstructure or foundation.

In one embodiment, a method of forming a nanostructure may compriseforming self-assembled nucleic acids on at least a portion of asubstrate, and repairing defects in the self-assembled nucleic acidsusing at least one repair enzyme. As a non-limiting example, the methodmay include process acts as shown in flow diagram 100 of FIG. 1.

As shown in the FIG. 1, nucleic acids configured and formulated to formthe predetermined self-assembled structures may be designed andsynthesized (101). Upon dissolving the nucleic acids into a solution,nucleic acids may form the predetermined self-assembled structuresthrough a complementary base pairing mechanism (102). Then, a pattern ofself-assembled nucleic acids may be formed on at least a portion of asubstrate (103). These self-assembled nucleic acids on the substrate mayinclude at least one defect. Optionally, the defects and the density ofdefects may be determined (104) using any conventional techniques. Thedefects in the self-assembled nucleic acids may be repaired using atleast one repair enzyme (105), to provide a nanostructure comprisingself-assembled nucleic acids on at least a portion of the substrateexhibiting a reduced defect density. The repairing of defects (104) maybe repeated as desired until a desired, reduced threshold level ofdefect density is achieved. Once the threshold level of defect densityis achieved, the resulting pattern of the self-assembled nucleic acidsmay be transferred to the substrate (106).

A computer software program may be used to design and identify thenucleic acid sequences that are capable of self-assembling into thedesired structures. The nucleic acids may be non-naturally occurringnucleic acids. The length and chemical makeup of the nucleic acidsequences may be selected depending on the desired self-assembledstructures to be formed.

Any conventional techniques may be used to synthesize nucleic acids, andtherefore such techniques are not described in detail herein. By way ofnon-limiting example, the nucleic acids may be synthesized usingautomated DNA synthesizer and phosphoramidite chemistry procedures.

Once synthesized, the nucleic acids may be dissolved into a solution.Upon dissolving in the solution, the nucleic acids may self-assembleinto the desired self-assembled structures through a complementary basepairing mechanism. Various self-assembled nucleic acids may be used inthe present disclosure.

In some embodiments, nucleic acids may self-assemble into a“multi-stranded” structure that is composed entirely of shortoligonucleotide strands. For example, as shown in FIG. 2A,self-assembled nucleic acids 201 are composed of short oligonucleotidestrands 201 a, 201 b and 201 c.

In some embodiments, nucleic acids may self-assemble into a “scaffolded”structure. The self-assembled “scaffolded” structure is composed of along single stranded polynucleotide (“scaffold strand”) that is foldedand bonded by a number of short strands of nucleic acids (“helperstrands”) into the desired structures. For example, as shown in FIG. 2B,self-assembled nucleic acids 202 are composed of a scaffold strand 202 athat is folded and fixed into a certain structure by the helper strands202 b, 202 b′, and 202 b″.

In some embodiments, nucleic acids may self-assemble into a“single-stranded” structure that is composed substantially of one longscaffold strand and few or no helper strands. For example, as shown inFIG. 2C, the self-assembled nucleic acid 203 is composed of one longscaffold strand 203 a.

It is understood that FIGS. 2A-2C show non-limiting example of theself-assembled nucleic acids, and that other self-assembled nucleicacids may be recognized by one skilled in the art.

The self-assembled nucleic acids may be formed on at least a portion ofa substrate using any conventional techniques. In some embodiments, theself-assembled nucleic acids may be formed on a substantially entireexposed surface of a substrate. Then, portions of the self-assemblednucleic acids on the substrate may be selectively removed, leaving theself-assembled nucleic acids only on the desired portions of thesubstrate. By way of non-limiting example, the self-assembled nucleicacids on the substrate may be selectively removed using conventionalmask techniques. In some embodiments, the self-assembled nucleic acidsmay be formed on the patterned regions of carbon on a silicon oxidebackground over a substrate.

In some embodiments, the self-assembled nucleic acids may be appliedonto at least a portion of the substrate by contacting at least aportion of the substrate with a solution comprising the self-assemblednucleic acids. By way of non-limiting example, a solution comprisingself-assembled nucleic acids may be applied to at least a portion of thesubstrate by spraying or coating techniques, or by dipping the substratein a solution comprising self-assembled nucleic acids.

In some embodiments, the self-assembled nucleic acids may be formed onat least a portion of a substrate by covalently coupling theself-assembled nucleic acids to the substrate. The nucleic acids in theself-assembled nucleic acids may include a coupling functional groupformulated and configured to form covalent bond with the substrate. Byway of example only, when the substrate is gold, silver, silicon dioxideor aluminum metalized features, the coupling functional group on thenucleic acid may be a primary amine. When the substrate is metal, thecoupling functional group on the nucleic acid may be an aminederivatized with a thiolation reagent such as succinimidyl3-(2-pyridyldithio)propionate (SPDP). When the substrate is silicondioxide, the coupling functional group on the nucleic acid may bedialdehyde derivatives of Schiff's base reaction. By way of anon-limiting example, when the substrate is glass or silicon dioxide(SiO₂), the substrate may be treated with dilute sodium hydroxidesolution. Then, the substrate may be contacted with a solution ofself-assembled nucleic acids that comprises 3-aminopropyltriethoxysilane(APS) group, to covalently couple the self-assembled nucleic acids tothe substrate via the APS group.

In some embodiments, the self-assembled nucleic acids may be formed onat least a portion of substrate by ionic attraction using anyconventional techniques. By way of a non-limiting example, magnesiumions (Mg²⁺) may be added to an aqueous solution of self-assemblednucleic acids. The positive charge Mg²⁺ attracts the negative charges onself-assembled nucleic acids, as well as the negative portions of thesubstrate. Thus, Mg²⁺ ions function to adhere the self-assembled nucleicacids to the negative portions of the substrate.

In addition to forming the self-assembled nucleic acids on at least aportion of a substrate via covalent bonds or ionic attractions asdescribed above, one of ordinary skill in the art recognizes that otherknown bonding techniques between the self-assembled nucleic acids and asubstrate may be used.

In some embodiments, at least a portion of the substrate may be exposedto a solution comprising self-assembled nucleic acids to provide ananostructure that comprises self-assembled nucleic acids on at least aportion of the substrate. Then, the nanostructure may be exposed againto a solution comprising self-assembled nucleic acids. The exposure tothe solution comprising self-assembled nucleic acids may be repeateduntil the desired thickness of the self-assembled nucleic acids on atleast a portion of the substrate is achieved.

The defect level, which may also be characterized as defect density, ofthe features on the substrate may then be determined, the defect levelcorresponding to defects in the pattern of self-assembled nucleic acids.The defects may be determined using any conventional technique such asoptical or e-beam based metrology techniques, and therefore suchtechniques are not described in detail herein.

The defects in the pattern of self-assembled nucleic acids may berepaired using at least one repair enzyme. The self-assembled nucleicacids on at least a portion of the substrate may be contacted with asolution comprising at least one repair enzyme. By way of non-limitingexample, the self-assembled nucleic acids on the at least a portion ofthe substrate may be exposed to a repair solution comprising at leastone repair enzyme by spraying or coating the self-assembled nucleicacids with the repair solution, or by dipping the substrate in therepair solution comprising at least one repair enzyme. The repair enzymemay be selected based at least in part on the identified defects in thepattern of self-assembled nucleic acids. The repair enzyme may bedissolved in an appropriate solvent, such as water, methanol, ethanol,or combinations thereof. The repair solution may include a sufficientconcentration of the repair enzyme to repair the defects.

The defects in the self-assembled nucleic acids on the at least aportion of substrate may be repaired by various mechanisms. By way ofnon-limiting example, the defects may be repaired by at least one offollowing mechanisms:

-   -   (a) a single step mechanism that involves a direct reversal by a        single enzyme, such as photolyase enzyme or O-6-methyl-DNA        alkyltransferase enzyme;    -   (b) a single-step or multi-step mechanism that involves base        excision, such as using glycosylase enzymes; and    -   (c) a multi-step mechanism that involves pleiotropic        specificities from multiple protein components.

With knowledge of the specific nucleic acids to be used in theself-assembled nucleic acids, the type of repair enzyme may be selectedby a person of ordinary skill in the art. Additionally, the repairenzyme may be formulated and configured to selectively repair certaindefects in the self-assembled nucleic acids.

In some embodiments, the repair enzyme may include an enzyme in ametallo-β-lactamase superfamily. The repair enzymes in this superfamilyusually bind a zinc ion (Zn²⁺), but in a few cases bind an iron ion(Fe²⁺), and catalyze the cleavage of C—N, O═O, C—S, and/or P—O bonds.These repair enzymes repair a defect that involves two divalent metalion binding sites. Non-limiting example of such repair enzymes mayinclude β-lactamase, oxidoreductase (rubredoxin/oxygen, ROO), glyoxalaseII, or artemis/DNA nuclease.

In some embodiments, the repair enzyme may include an enzyme in ahaloacid dehalogenase superfamily. The repair enzymes in thissuperfamily catalyze the cleavage and formation of C—Cl, C—P, and/or P—Obonds. These repair enzymes repair a defect that involves aspartatenucleophile and a general base. Non-limiting example of such repairenzymes may include haloacid dehalogenase, phosphonatase, Ca²⁺-ATpase,or DNA 3′-phosphatase.

In some embodiments, the repair enzyme may include an enzyme in an Fe(II)/α-ketoglutarate-dependent dioxygenase superfamily. The repairenzymes in this superfamily catalyze the cleavage of C—S and C—N bonds,or formation of C—N, C—O, and C—S heterocycle structure. These repairenzymes repair a defect that involves a single divalent metal ionbinding site. Non-limiting example of such repair enzymes may includeclavimate synthase, isopenicillin synthase, taurine dioxygenase, orAlkB.

Accordingly, a method of forming a nanostructure comprises forming apattern of self-assembled nucleic acids on at least a portion of asubstrate. The method further comprises exposing the pattern ofself-assembled nucleic acids on the at least a portion of the substrateto at least one repair enzyme to repair defects in the self-assemblednucleic acids.

The repairing of defects in the self-assembled nucleic acids on at leasta portion of a substrate may be repeated until a desired, reducedthreshold level of the defect density is achieved. The defects may berepaired by repeatedly exposing the self-assembled nucleic acids on thesubstrate to the repair solution. By way of example only, the repairsolution may be contacted with the self-assembled nucleic acids betweenone time and ten times. As the concentration of repair enzyme in arepair solution decreases, a freshly made solution of the repair enzymehaving a higher concentration may be employed in substitution for theinitial repair solution.

Accordingly, a method of forming a nanostructure comprises formingself-assembled nucleic acids on at least a portion of a substrate,wherein the self-assembled nucleic acids exhibits an initial defectdensity. The method further comprises contacting the self-assemblednucleic acids on the at least a portion of a substrate with a solutioncomprising at least one repair enzyme to repair defects in theself-assembled nucleic acids. The method further comprises repeating therepair of defects in the self-assembled nucleic acids until a desired,reduced threshold level of defect density is achieved.

In some embodiments, the defect in the self-assembled nucleic acids onat least a portion of a substrate may be repaired using more than onerepair enzyme. In such embodiments, the self-assembled nucleic acid onthe at least a portion of a substrate may be exposed to repair solutionsincluding different repair enzymes simultaneously or consecutively tolower the defect density in the self-assembled nucleic acids on the atleast a portion of a substrate.

Accordingly, a method of decreasing a defect density in self-assemblednucleic acids on at least a portion of a substrate comprises repairingdefects in self-assembled nucleic acids on at least a portion of asubstrate by exposure to at least one repair enzyme.

Once the threshold level of the defect density is achieved, theresulting pattern of the self-assembled nucleic acids may be transferredto the substrate. The self-assembled nucleic acids may function asnano-scale templates or masks having operative dimensions of less thanabout 50 nm to transfer the desired pattern to the substrate.

FIGS. 3A-3C show various stages for a method of using the self-assemblednucleic acids as nano-scale templates or masks to transfer the desiredpattern to the substrate.

FIG. 3A shows a semiconductor structure 300 that includes a substrate301, a hardmask material 303 overlying the substrate 301, and a patternof self-assembled nucleic acids 302 over the hardmask material 303. InFIG. 3B, the pattern of self-assembled nucleic acids 302 is transferredto the hardmask material 303, thus the pattern of self-assembled nucleicacids 302 may function as a nano-scale template. At least a portion ofthe substrate 301 may be selectively removed using the self-assemblednucleic acids 302 as the template/mask to protect at least a portion ofthe substrate 301 from an etchant (such term being non-limiting, andencompassing liquid and gaseous fluid compositions suitable to removesubstrate material exposed through apertures in the template) to providea semiconductor structure 400 that includes a modified substrate 401 andthe overlying mask comprising the pattern of self-assembled nucleicacids 302 and the hardmask material 303. Then, as shown in FIG. 3C, theself-assembled nucleic acids 302 and the hardmask material 303 may beremoved. By way of example only, the self-assembled nucleic acids 302may be removed by a heat treatment at a temperature of from about 90° C.to about 200° C., or by an acidic solution.

Accordingly, a method of forming a nanostructure comprises forming amask comprising a pattern of self-assembled nucleic acids over at leasta portion of substrate surface, and removing at least a portion of thesubstrate exposed through the pattern of the mask.

The modified substrate 401 may be further processed for the fabricationof components on the substrate, such as by way of non-limiting example,silicon nanowires, gold nanoparticles, semiconductive quantum dots, orfluorescent quantum dots.

Accordingly, a method of forming a nanostructure comprises forming amask comprising a pattern of self-assembled nucleic acids over at leasta portion of a substrate surface. The method further comprises forming ananocomponent on at least a portion of the substrate exposed through thepattern in the mask. The nanocomponent comprises a material selectedfrom the group consisting of nanowires, gold nanoparticles,semiconductive quantum dots, and fluorescent quantum dots.

In some embodiments, the self-assembled nucleic acids may be used toform features on the substrate having dimensions of less than about 50nm and exhibiting a low defect density. By way of example only, thefeatures on the substrate may have dimensions of less than about 40 nm,less than about 30 nm, less than about 20 nm, or less than about 10 nm.The nanostructure comprising self-assembled nucleic acids may besubjected to further processing for fabrication of the desired devices.In some embodiments, the self-assembled nucleic acids may be removedduring further processing acts.

Accordingly, a semiconductor structure comprises a pattern ofself-assembled nucleic acids defining a template having at least oneaperture therethrough, the at least one aperture comprising at least onedimension of less than about 50 nm.

While the present disclosure is susceptible to various modifications andalternative forms, specific embodiments have been shown by way ofexample in the drawings and have been described in detail herein.However, the present disclosure is not intended to be limited to theparticular forms disclosed. Rather, the present disclosure is to coverall modifications, equivalents, and alternatives falling within thescope of the present disclosure as defined by the following appendedclaims and their legal equivalents.

What is claimed is:
 1. A method of forming a structure, comprising:forming a pattern of self-assembled nucleic acids over a material;exposing the pattern of self-assembled nucleic acids to at least onerepair enzyme to repair defects in the pattern of self-assembled nucleicacids; and transferring the repaired pattern of self-assembled nucleicacids to the material to form features therein.
 2. The method of claim1, wherein forming a pattern of self-assembled nucleic acids over amaterial comprises forming the pattern of self-assembleddeoxyribonucleic acids or the pattern of self-assembled ribonucleicacids over the material.
 3. The method of claim 1, wherein forming apattern of self-assembled nucleic acids over a material comprisesforming the pattern of self-assembled nucleic acids over a carbonmaterial.
 4. The method of claim 1, wherein forming a pattern ofself-assembled nucleic acids over a material comprises covalentlybonding the self-assembled nucleic acids to the material.
 5. The methodof claim 1, wherein forming a pattern of self-assembled nucleic acidsover a material comprises ionically bonding the self-assembled nucleicacids to the material.
 6. The method of claim 1, wherein transferringthe repaired pattern of self-assembled nucleic acids to the material toform features therein comprises forming the features comprising at leastone dimension of less than about 40 nm.
 7. A method of forming astructure, comprising: forming a mask of self-assembled nucleic acidsover a material; contacting the mask of self-assembled nucleic acidswith at least one repair enzyme to repair defects in the mask ofself-assembled nucleic acids; and removing the material exposed throughthe mask of self-assembled nucleic acids to form features therein. 8.The method of claim 7, wherein forming features in the materialcomprises forming the features in the material comprising a lower defectlevel than in the mask of self-assembled nucleic acids.
 9. The method ofclaim 7, wherein forming features in the material comprises formingnanowires, gold nanoparticles, semiconductive quantum dots, orfluorescent quantum dots in the material.
 10. The method of claim 7,further comprising removing the mask of self-assembled nucleic acids.11. A method of forming a structure, comprising: self-assembling nucleicacids on a material to form an initial self-assembled nucleic acidpattern; contacting the initial self-assembled nucleic acid pattern withat least one repair enzyme to repair defects in the initialself-assembled nucleic acid pattern; and transferring the repairedself-assembled nucleic acid pattern to the material.
 12. The method ofclaim 11, wherein self-assembling nucleic acids on a material to form aninitial self-assembled nucleic acid pattern comprises forming theinitial self-assembled nucleic acid pattern comprising multi-strandedoligonucleotide strands.
 13. The method of claim 11, whereinself-assembling nucleic acids on a material to form an initialself-assembled nucleic acid pattern comprises forming the initialself-assembled nucleic acid pattern comprising a single strandedpolynucleotide folded and bonded into a scaffolded structure.
 14. Themethod of claim 11, wherein self-assembling nucleic acids on a materialto form an initial self-assembled nucleic acid pattern comprises formingthe initial self-assembled nucleic acid pattern comprising a singlestranded polynucleotide.
 15. The method of claim 11, wherein contactingthe initial self-assembled nucleic acid pattern with at least one repairenzyme comprises achieving a reduced defect density in the repairedself-assembled nucleic acid pattern.
 16. The method of claim 15, whereintransferring the repaired self-assembled nucleic acid pattern to thematerial comprises transferring the repaired self-assembled nucleic acidpattern to the material after achieving the reduced defect density. 17.A method of decreasing defect density in self-assembled nucleic acids,the method comprising: forming self-assembled nucleic acids over atleast a portion of a material, the self-assembled nucleic acidsexhibiting an initial defect density; and exposing the self-assemblednucleic acids to at least one repair enzyme to repair defects in theself-assembled nucleic acids.
 18. The method of claim 17, whereinexposing the self-assembled nucleic acids to at least one repair enzymeto repair defects in the self-assembled nucleic acids comprises removingat least one base from the self-assembled nucleic acids.
 19. The methodof claim 17, wherein exposing the self-assembled nucleic acids to atleast one repair enzyme to repair defects in the self-assembled nucleicacids comprises repairing at least one metal ion binding site in theself-assembled nucleic acids.
 20. The method of claim 17, furthercomprising repeating the exposing the self-assembled nucleic acids to atleast one repair enzyme until a reduced defect density is achieved.